The real hydrogen highway: the future looks like today

The Canadian hydrogen-highway industry is at a crossroads. Compared with the rest in the world Canada is a fading champion in the hydrogen arena. Though the famous Ballard Power started here in Canada, the public funding that kept the venture alive and in the headlines has all but dried up. But there’s still hope for a comeback. Its success depends on whether hydrogen proponents are able to expand their vision of how we will use hydrogen in the future.

Almost all proponents of the hydrogen highway envision using hydrogen as a stand-alone transportation fuel. Most scenarios are based on one of two applications. In one application, hydrogen generates electricity (through a fuel cell) that drives an electric motor which in turn powers the car. In the other application, hydrogen is burned directly as a liquid fuel in an internal combustion engine.

In either case, the exhaust product is only water—no harmful emissions. This above all gives the currently envisioned hydrogen highway its allure. It promises pollution-free, and guilt-free, driving.

(Before I tear this idea apart, I should say that hydrogen absolutely will deliver on this promise when it comes to rail transportation. Trains can carry enormous amounts of cargo, and as we’ll see this ability removes one of the major hurdles to stand-alone hydrogen: the difficulty of storing it in fuel tanks of reasonable size. You need more space on a train? Add another car.)

The problem is, to realize the utopia of emission-free car transportation, we’ll have to bridge a yawning technological chasm. Compared with gasoline, stand-alone hydrogen packs more oomph by weight—forty kilograms of hydrogen will take you further than 40 kg of gasoline. But hydrogen is a gas at most temperatures. This inescapable physical fact means it’s not easy to get that 40 kg of hydrogen into a fuel tank the same size as one that holds 40 kg of gasoline. You have to super-cool it, and then super-pressurize it.

What material would the fuel tank have to be made of, to safely and effectively hold this super-cooled, super-pressurized hydrogen? We don’t know. The American Physical Society, commenting on former president Bush’s fuel cell initiative, said we’ll have to develop that material first. And for that to happen, “major scientific breakthroughs are needed.”

In the mean time, cars that run on pure hydrogen will need very big fuel tanks. This will either increase the size of the car, or decrease passenger space. Either way, hydrogen as a stand-alone fuel does not currently meet the “fungibility criterion.” Motorists have come to expect a 100 x 67 x 25 cm fuel tank to hold enough fuel to carry them 450–500 kilometers. To be able to drive that distance on pure hydrogen from a similar-size tank, you’d have to stop and fill up three or four times. That’s not what anybody would call fungible. Give a motorist the choice at the gas pump, and she’ll choose gasoline every time.

I mentioned at the beginning that the hydrogen highway can make a comeback in Canada, but that current proponents will have to expand their vision of how we will use hydrogen. One way they can do this is to revisit the issue of hydrogen storage. Instead of inventing a new super-material that will store super-cooled, super-pressurized pure hydrogen, they should look down the quantum ladder, beyond the micro- or nano-level—right down to the molecular level. At the molecular level, we don’t need to invent a new hydrogen storage material. We already have one. It’s called carbon. An “average” gasoline molecule is C₈H₁₈.

I’m not being glib. And I’m not suggesting that the status quo is fine. The problem with current hydrocarbon fuels is that they put new carbon (and sulfur and other bona fide pollutants) into the atmosphere. I say “new” carbon because current hydrocarbon fuels are made from petroleum, and every liter of petroleum gasoline that is burned in a car engine emits 2.3 kilograms of CO₂. That’s new carbon.

But if the carbon part of the C₈H₁₈ molecule were recycled carbon, the environmental impact of using this kind of gasoline would be dramatically reduced.

You can be forgiven for not seeing much of a difference between synthetic gasoline made from recycled carbon and today’s status quo. There’s really nothing futuristic about it. But this is precisely why this vision is more practical, credible—and likely—than the ones that envision pure hydrogen. Synthetic gasoline would work in the exact same types of engines as today. Distributors and retailers would distribute and sell it in exactly the same way they do today. The motorists that pump it into their cars would see no difference at all.

And it gets better. If the hydrogen component of our C₈H₁₈ molecule were manufactured by splitting water using low- or zero-carbon processes, then—in combination with the recycled carbon component—there would be a massive environmental difference between this synthetic gasoline and the petroleum-based stuff we use today.

Recently, the major German carmakers—Audi, BMW, Volkswagen, Porsche, Daimler, Ford Europe, and GM Europe—told the press about their efforts to reduce transportation CO₂. They differed on how quickly the electric powertrain will come to displace the internal combustion engine, but it is surprising to see how many view the fuel cell as the central technology of the future. The main hurdle, they said, is the lack of fueling infrastructure.

I think they are underestimating the size and sequence of their hurdles. There are actually three of them. First, there is no water splitting process that produces carbon-free hydrogen on a scale sufficient to supply even a fraction of what is needed. Unless and until such a process enters the industry and proves viable, hydrogen cannot and will not play a central role in the transportation economy of the future.

Second, as I mentioned above, there is no material—other than carbon at the molecular level—that can contain hydrogen in a way that makes its performance similar to conventional fuels.

The lack of a refueling infrastructure for pure hydrogen is a distant third hurdle. To cross it, you have to cross the first two. And since you have to solve the problems of hydrogen production and storage first, I think the automakers ought to at least have a look at synthetic fuel made from recycled carbon.

Recycled from what? Stay tuned.